This invention relates to carpenters' tools, particularly to carpentry layout squares having an integral level, and measuring and marking elements corresponding to standard dimensions of construction materials, arranged to permit the layout of angular and linear dimensions using a single tool and to ease the framing of walls and the construction of roofing.
Various types of carpentry squares are widely used in many fields of construction. They are generally used to fit two pieces of material together perpendicularly, to square adjacent edges of, for example, a piece of lumber, and to mark lumber for framing walls. In addition, together with a level, carpentry squares are often used in determining or establishing the pitch of a roof in constructing and modifying roofs.
A framing square is one type of carpentry square. A typical framing square consists of a single piece of material formed in the shape of an "L", that is, two legs of unequal length joined to each other at a right angle, each leg having markings to indicate increments of linear measurement, these legs usually being between one and two feet long. Variations on the framing square provide integrated levels or at least one additional, usually adjustable leg.
Previously known forms of framing squares are subject to certain limitations. The typical framing square, while of simple construction and capable of straightforward use, tends to be overly bulky, and cannot readily be used to layout rafters in roofs or to plumb studs or level beams in framing walls without the simultaneous use of a leveling device. In addition, while the length of the typical framing square's legs is useful with respect to the long dimensions common to materials used in construction of buildings, the squares generally do not provide structure that relates the dimensions of the square's legs to the standard width and thickness dimensions of lumber, which dimensions are critical in laying out joints.
Those framing squares that integrate a leveling device with a framing square generally fail either to overcome the bulkiness limitation, to relate the dimensions of the square's legs to standard lumber dimensions, to provide structure that readily tolerates the angular layout of rafters or, if structure is provided that allows angles to be measured, to provide such structure so that the square can be used simultaneously to measure angular dimensions of rafters while laying out other roof members. Examples of the foregoing can be found in Whiteford U.S. Pat. No. 4,503,624 and Thibodeoux U.S. Pat. No. 4,394,801. Those squares that include scales for laying out angular dimensions similarly generally fail to provide structure that allows the square to be used simultaneously to measure angular dimensions of rafters while laying out other roof members. An example of the foregoing can be found in Russo U.S. Pat. No. 4,151,650.
Other squares increase the functionality of the typical framing square by adding a third leg. These squares tend to be of complex construction, with one or more legs being angularly or linearly adjustable and sometimes include a leveling device or other features. These squares tend to be difficult to use because of their complexity. Moreover, they do not provide structure that relates the dimensions of the square's legs to the standard width and thickness dimensions of lumber, which dimensions are critical in laying out joints. In addition, those squares that include a leveling device, though usable to measure the angular dimensions of rafters in constructing roofs, are not well constructed for the layout of the rafters and other roof members. Examples of the foregoing can be found in Herkimer U.S. Pat. No. 4,813,149 and Hopfer 4,697,351.
Because known conventional layout squares each have inherent limitations to their usefulness, a need exists for an improved layout square which more readily facilitates framing of structures.